1. Field of the Invention
The present invention relates to an ice storage detection switch, and more particularly to a switch for detecting an ice level in an ice storage chamber of an ice making machine.
2. Description of the Related Art
In an ice making machine for storing blocks of ice produced by an ice making portion in an ice storage chamber, an ice storage detection switch as shown in, for example, FIG. 5 is installed in the ice storage chamber. This ice storage detection switch is intended to detect the ice level in the ice storage chamber and stop operation of the ice making machine. In this ice storage detection switch, a switch lever 2 is rotatably fitted about a rotational center 3 on the ice storage chamber side of a switch case 1 fixed to a wall surface or the like of the ice making chamber (e.g., see Japanese Utility Model Application Laid-open No. 1-151177).
As shown in FIG. 6a, in the switch case 1, a reed switch 5 is embedded in a reed switch holding portion 4 formed protrusively toward the switch lever 2. On the other hand, a magnet lever 6 is rotatably fitted to a back surface of the switch lever 2, and a magnet 7 is held by the magnet lever 6. The switch lever 2 assumes a rotational position shown in FIG. 6a due to its own weight when the ice level in the ice storage chamber is lower than an installation height of the ice storage detection switch and no force is applied from the blocks of the ice to the switch lever 2. In this case, the magnet 7 held by the magnet lever 6 is disposed in close vicinity of the reed switch 5, which is ON.
When the ice level in the ice storage chamber rises approximately up to the installation height of the ice storage detection switch as the production of the ice by the ice making portion progresses, the switch lever 2 is pressed by the blocks of the ice and its rotational position gradually shifts toward the switch case 1 as shown in FIGS. 6b to 6d. In accordance with the shift of the rotational position of the switch lever 2, the magnet lever 6 comes into abutment with a corner portion of the reed switch holding portion 4 and rotates, so the magnet 7 held by the magnet lever 6 separates from the reed switch 5. The reed switch 5 is turned OFF as a result of a change in a clearance between the reed switch 5 and the magnet 7 at this moment, and outputs an ice storage detection signal. Based on this ice storage detection signal, the operation of the ice making machine is stopped.
In the conventional ice storage detection switch shown in FIG. 6a, however, the magnet lever 6 comes into abutment with the corner portion of the reed switch holding portion 4 to thereby rotate, the amount of change in the clearance between the reed switch 5 and the magnet 7 at the time when the switch lever 2 is pressed toward the switch case 1 is small. When variation of sensitivity exists across the reed switch 5, there is a fear in that the ON/OFF operation may not be performed accurately. For instance, the operational reliability of the ice making machine deteriorates if the reed switch 5 is not turned OFF even when the switch lever 2 is pressed to the extent of coming into abutment with the switch case 1 as shown in FIG. 6d, or if the reed switch 5 is not turned ON even when the switch lever 2 has returned to its unpressed state as shown in FIG. 6a. 